boc morpholino (MO) injections cause uml-like defects. (A) A control MO-injected 48 hpf embryo. (B) uml mutants have curved body axes at this stage. (C) Injection of a translation blocking boc MO results in a curved body axis similar to that seen in uml mutants. (D) Normal nkx2.2a expression in the ventral forebrain and midbrain (arrowhead) of a control MO-injected embryo. (E) Regional loss of nkx2.2a expression seen in uml mutants (arrowheads). (F) Injecting boc MO results in the loss of nkx2.2a expression in the same regions as in uml mutants (arrowheads). (G) Zn-5 antibody labeling at 48 hpf showing RGC axons that have crossed the midline by 48 hpf to form the optic chiasm (arrowhead). (H) In uml mutants, RGC axons fail to cross the midline (arrowhead) and grow aberrantly in the ventral forebrain (arrows). (I) boc MO injections can result in specific retinal axon defects (arrowheads) that are remarkably similar to those seen in uml. A-C are lateral views of live zebrafish. D-F are lateral views of the head, eyes removed, anterior to the left. G-I are ventral views of the head, anterior uppermost.